Talking About What You Did in Japan

How to form negative sentences:
-ます [masu] → -ません [masen]

• します [shimasu] I do it. → しません [shimasen] I don't do it.
• あります [arimasu] there is → ありません [arimasen] there isn't

卵はありません [tamago wa arimasen]
There aren't any eggs.

• 卵 [tamago] means "eggs"
• は [wa] is the particle that marks the subject
• ありません [arimasen] means "there aren't"
• Literally means "eggs, there aren't"

How to form negative sentences into past tense:
-ません [masen] → -ませんでした [masen deshita]

ありませんでした [arimasen deshita]
There weren't any.

• ありません [arimasen] means "there aren't"
• でした [deshita] means "was"

しませんでした [shimasen deshita]
I didn't do it.

• しません [shimasen] means "I don't do it"

• A: 先週は宿題しましたか
  Did you do homework last week?
• B: いいえ。しませんでした [iie. shimasen deshita]
  No, I didn't do it.
• A: 昨日は本を読みましたか
  Did you read a book yesterday?
• B: いいえ、読みませんでした [iie, yomimasen deshita]
  No, I didn't read it.